Review Recent research in myalgic encephalomyelitis/chronic fatigue syndrome: an evidence map 2025 Todhunter-Brown et al

Background
Myalgic encephalomyelitis/chronic fatigue syndrome is a chronic condition, classified by the World Health Organization as a nervous system disease, impacting around 17 million people worldwide. Presentation involves persistent fatigue and postexertional malaise (a worsening of symptoms after minimal exertion) and a wide range of other symptoms. Case definitions have historically varied; postexertional malaise is a core diagnostic criterion in current definitions. In 2022, a James Lind Alliance Priority Setting Partnership established research priorities relating to myalgic encephalomyelitis/chronic fatigue syndrome.

Objective(s)
We created a map of myalgic encephalomyelitis/chronic fatigue syndrome evidence (2018–23), showing the volume and key characteristics of recent research in this field. We considered diagnostic criteria and how current research maps against the James Lind Alliance Priority Setting Partnership research priorities.

Methods
Using a predefined protocol, we conducted a comprehensive search of Cochrane, MEDLINE, EMBASE and Cumulative Index to Nursing and Allied Health Literature. We included all English-language research studies published between January 2018 and May 2023. Two reviewers independently applied inclusion criteria with consensus involving additional reviewers.

Studies including people diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome using any criteria (including self-report), of any age and in any setting were eligible. Studies with < 10 myalgic encephalomyelitis/chronic fatigue syndrome participants were excluded.

Data extraction, coding of topics (involving stakeholder consultation) and methodological quality assessment of systematic reviews (using A MeaSurement Tool to Assess systematic Reviews 2) was conducted independently by two reviewers, with disagreements resolved by a third reviewer. Studies were presented in an evidence map.

Results
Of the 11,278 identified studies, 742 met the selection criteria, but only 639 provided sufficient data for inclusion in the evidence map. These reported data from approximately 610,000 people with myalgic encephalomyelitis/chronic fatigue syndrome. There were 81 systematic reviews, 72 experimental studies, 423 observational studies and 63 studies with other designs. Most studies (94%) were from high-income countries. Reporting of participant details was poor; 16% did not report gender, 74% did not report ethnicity and 81% did not report the severity of myalgic encephalomyelitis/chronic fatigue syndrome. Forty-four per cent of studies used multiple diagnostic criteria, 16% did not specify criteria, 24% used a single criterion not requiring postexertional malaise and 10% used a single criterion requiring postexertional malaise. Most (89%) systematic reviews had a low methodological quality.

Five main topics (37 subtopics) were included in the evidence map. Of the 639 studies; 53% addressed the topic ‘what is the cause?’; 38% ‘what is the problem?’; 26% ‘what can we do about it?’; 15% ‘diagnosis and assessment’; and 13% other topics, including ‘living with myalgic encephalomyelitis/chronic fatigue syndrome’.

Discussion
Studies have been presented in an interactive evidence map according to topic, study design, diagnostic criteria and age. This evidence map should inform decisions about future myalgic encephalomyelitis/chronic fatigue syndrome research.

Limitations
An evidence map does not summarise what the evidence says. Our evidence map only includes studies published in 2018 or later and in English language. Inconsistent reporting and use of diagnostic criteria limit the interpretation of evidence. We assessed the methodological quality of systematic reviews, but not of primary studies.

Conclusions
We have produced an interactive evidence map, summarising myalgic encephalomyelitis/chronic fatigue syndrome research from 2018 to 2023. This evidence map can inform strategic plans for future research. We found some, often limited, evidence addressing every James Lind Alliance Priority Setting Partnership priority; high-quality systematic reviews should inform future studies.

Open access

 

The link to the Supplementary material takes me to this page:
https://apps.crossref.org/pendingpub/pendingpub.html?doi=10.3310/BTBD8846

Are anyone able to access the material?

 

Seems to not be published yet. Should be published soon.

 

https://njl-admin.nihr.ac.uk/document/download/2047460

Plain language summary Health Technology Assessment 2025 (Plain language summary)

What was the question?

Myalgic encephalomyelitis/chronic fatigue syndrome is a long-term condition with many different symptoms. People with myalgic encephalomyelitis/chronic fatigue syndrome have exhaustion, stopping them from doing activities and having a big impact on everyday life. They also have postexertional malaise, meaning they become more unwell after using even small amounts of energy. Myalgic encephalomyelitis/chronic fatigue syndrome is not well understood. The symptoms needed for a professional to tell someone that they have myalgic encephalomyelitis/chronic fatigue syndrome have changed over time. Now, people have to experience postexertional malaise to confirm myalgic encephalomyelitis/ chronic fatigue syndrome, but this has not always been the case. We wanted to bring together recent research on myalgic encephalomyelitis/chronic fatigue syndrome and explore the numbers of studies and the topics that were scrutinised. What did we do? We searched for all the studies on myalgic encephalomyelitis/chronic fatigue syndrome that were published between January 2018 and May 2023. We brought together information about these studies. We grouped research studies based on the topics they investigated. We made an interactive map that shows all these myalgic encephalomyelitis/chronic fatigue syndrome studies. The map has filters to let people explore the studies that have only included the people with postexertional malaise.

What did we find? Our map contains 639 studies that have studied over 600,000 people with myalgic encephalomyelitis/chronic fatigue syndrome.
The main topics we looked at were:
• ‘what is the cause?’ (53% of studies)
• ‘what is the problem?’ (38% of studies)
• ‘what can we do about it?’ (26% of studies)
• ‘diagnosis and assessment’ (15% of studies).
Some studies looked at more than one topic. Studies do not always report things clearly. Some do not explain how it was decided if someone had myalgic encephalomyelitis/chronic fatigue syndrome; 11% of studies only included people with postexertional malaise.

How can this help? This map of myalgic encephalomyelitis/chronic fatigue syndrome studies can help plan future research. Knowing the numbers of studies looking at different topics can help plan what research to do next

 

Sorry, but I cannot see why. Planning good research requires persistent, deep and unbiased thought.

 

This might sound more convincing...

...if it hadn't been preceded by this.

I suppose it's helpful to know it's not clear what was even being studied in 89% of them, let alone whether there's any point revisiting the ground they covered.